Vitamin B12

Dr. Amanda Capasso

Vitamin B12

The Basics:

Vitamin B12 is a water-soluble vitamin that cannot be made by the human body. As humans, the only way to get this essential vitamin is through diet or supplementation. Animal products including meat, poultry, fish, eggs and dairy, naturally contain vitamin B12. Vitamin B12 is bound to protein molecules and has to be freed from those proteins by our stomach acid to allow for absorption in the small intestine. Anyone can be at risk of low B12 but vegans, vegetarians, those who have undergone weight-loss surgery, the elderly and patients on stomach acid suppressing medications (H2 receptor antagonists, proton pump inhibitors) and the popular type-two diabetes medication, metformin, are at particular risk of vitamin B12 deficiency.

B12 Deficiency:

Vitamin B12 plays an essential role throughout the body. Most notably, it assists in DNA formation, nerve protection, energy production and decreases the cardiovascular risk factor marker, homocysteine. Low B12 can lead to certain anemias, neurological disorders and higher risk of cardiovascular disease. Common symptoms include; fatigue, brain fog, anxiety/depression and if the deficiency is severe enough, it can cause numbness and tingling in the hands and feet. Your liver will store extensive amounts of B12 so it can take up to five years of deficiency before symptoms present, which is why it is important to ask your doctor to check your B12 levels annually.


Four forms of vitamin B12 exist but for simplicity sake, I’ll discuss the two most commonly recommended forms of B12- methylcobalamin and cyanocobalamin. Methylcobalamin is the active form of B12 that is naturally found in the human body. Cyanocobalamin is a synthetic form of B12 that our bodies convert into methylcobalamin. Unfortunately, some people are genetically pre-dispositioned to be poor converters and don’t get adequate levels of methylcobalamin. Taking the active form of B12 circumvents wondering if you are a poor converter or not. In Canada, low b12 is treated either with oral supplementation or B12 injections. Research shows that a 1mg B12 injection, once a week for eight weeks will increase serum B12 levels the same amount as a 1mg oral daily supplement taken for four months. Oral supplementation is a cheap and effective way to increase your B12 but weekly injections should be considered by patients with low stomach acid or digestive issues, patients who need to get serum levels up quickly and those who have low compliance taking oral supplements.

If you’re wondering about your vitamin B12 status and/or are interested in B12 injections, a naturopathic doctor who has written and passed the Ontario Prescribing and Therapeutics exam can help!